HEV is an ss(+)RNA virus causing self-limited hepatitis in human. When expressed in insect Tn5 cells, the truncated capsid protein (CP) covering residues 112-608 is able to self-assemble into virus-like particle (VLP). The VLP is smaller than the HEV native virion and contain no HEV genomic RNA. The VLP itself induces efficiently the immunity in chimpanzee against the challenge of HEV virus without adjuvant. The structure of this HEV VLP has recently been achieved in atomic resolution by the present inventors to elucidate that HEV CP is composed of three major domains, S1, S2, and P, with epitope presentation and capsid assembly modularized in independent modalities (Wang et al., 2008. Acta Crystallographica F, Acta Cryst. F 64, 318-322; Xing et al., 1999. Virology 265, 35-45). HEV VLP is a potential carrier of mucosal vaccine for the presentation of antigenic epitopes through oral administration. The chimeric CP, with an insertion of 11 amino acids of a B-cell epitope tag at the C-terminus of a truncated CP, still forms icosahedral particle. After oral administration, this HEV chimeric VLP is able to stimulate humoral immune response and significant level of IgM and IgG antibodies to the inserted epitope and HEV were observed in intestinal secretions (Niikura et al., 2002. Virology 293, 273-280). Importantly, the HEV VLP can disassemble and reassemble in vitro with the ability of encapsidating DNA plasmids. With this method, the HEV VLP is demonstrated to deliver DNA plasmid encoding human immunodeficiency virus (HIV) gp120 into the intestinal mucosa. Significant level of specific IgG and IgA to HIV env was found in fecal extracts and sera of testing experimental animal. Moreover, mice used in the study exhibited CTL response specific to gp120 in the spleen, Payer's patches and mesenteric lymph modes (Takamura, S., et al., 2004. Gene Ther 11, 628-63). In summary, these data demonstrate that the HEV VLP is capable of delivering both amino acid antigens and DNA encoding the antigens to or conferring immunity to mucosal tissue by oral administration.